A comprehensive evaluation of sampling systems and sampling efficiencies of lab-scale applied biotechnology systems has been performed. A planned evaluation of ACABS' bioreactor system was completely defaulted due to Force Majeure; the international TENIRS system could however be evaluated in full. Surprising results ensued: the TENIRS sampling devise is inaccurate and highly sensitive to operating conditions -- while showing an almost constant reproducibility. This sampler is in point of fact precisely wrong. The evaluation comprised three kinds of model-systems composed by polymer/water: light particles, heavy particles, and a mixture of both, concluding with a synthetic manure, all spanning realistic dry matter concentrations. The bias increases with complexity of the multi-phase system, but decreases with respect to the circulation speed in the TENIRS measuring loop. Composite samples of synthetic manure -- the most realistic model-systems evaluated -- composed of 10 increments extracted at low speed (20% of the top circulation speed) can present a bias as high as 320% whereas composite samples of light pellets extracted in the same conditions reaches some 85%. At higher speed (60% of the top circulation speed), the bias observed for the synthetic manure was 15% while being significantly negative, -70% for model-systems based on the heavy model system particles. These findings have severe implications regarding the necessity of redesigning the TENIRS reference sampling system completely. Acoustic chemometrics was used to model the dry matter concentration of these lots. All models were test set validated. Promising results were obtained: synthetic manure displays a prediction vs. reference slope of 0.89 and a correlation coefficient, r² of 0.89 -- demonstrating acoustic chemometrics as a powerful potential PAT modality concerning physical Y-variables. Much work on acoustic chemometrics on this type of applied biotechnological systems remains. A review of PAT modalities is also given with special focus on applied biotechnological system.